"His biggest strength is probably his versatility," assistant general manager Jeff Kingston said. "He can play just about anywhere in the diamond and he'll give us depth mostly in the middle infield down in Tacoma, especially if Willie [Bloomquist] can't go at the start of the season."
O'Malley becomes the fourth veteran to receive a non-roster invitation from the Mariners, joining pitchers Mark Lowe and Justin Germano and third baseman Carlos Rivero.
The Mariners also have extended non-roster camp invitations to 11 of their own Minor League players. That group, announced Thursday, includes top infield prospect D.J. Peterson, outfielders Patrick Kivlehan and Jordy Lara and catchers Steven Baron, Mike Dowd and Tyler Marlette.
Non-roster pitchers invited to camp will be Sam Gaviglio, Stephen Landazuri, Tyler Olson, Jordan Pries and Forrest Snow. Pitchers and catchers will report to Peoria, Ariz., on Feb. 20.
The club will continue to pursue other veteran free agents on non-roster deals. Outfielder Endy Chavez is a good possibility to return for a third year on a Minor League deal, though no deal has been confirmed.
Outfielder Franklin Gutierrez's agent has indicated Gutierrez would like to play in 2015 after sitting out last year, according to Kingston, and the Mariners have had some discussions about his possible return as a non-roster invitee after receiving positive reports on his play in the Venezuelan Winter League.
In other Mariners news:
• The club announced that a record 16 Cactus League games will be televised by ROOT Sports this spring, a big jump from the normal six or seven, starting with the first two contests against the Padres on March 4-5 from Peoria.
Thirty of the 32 Cactus League games will be carried on 710 ESPN Seattle radio, with 20 of those games lives and the other 10 on tape delay.
• Trainer Rick Griffin said Bloomquist is "progressing very nicely" from his right knee surgery and began a running program in Arizona about two weeks ago. The utility infielder will likely be limited early in spring, but Griffin said he anticipates the veteran will be ready to go when games begin.
• Left-hander Danny Hultzen shouldn't have any limitations as he returns to the mound after missing all last year following shoulder surgery, though general manager Jack Zduriencik said it's unrealistic to expect the 2011 first-round Draft pick to be ready for Major League action to start the year after being out for so long.